Hi All, I'm building an autograding framework for my biostatistics class this semester, and I am exploring different ways to automatically grade figures.
In other classes, I teach ggplot2 and I extract information directly from the ggplot2 object. However, in this class we are using base R and I need to extract information from base-r graphics. I've tried several different approaches, but I'm not sure which one is the easiest and most effective. Has anyone ever tried this? Are there any packages to help with this? (1) Storing `recordedplots` objects and trying to extract information from them. This data structure felt very low level, and I wasn't sure how easy it was to map the results to user-level function calls. (2) Use the `svglite` device to produce svg files, which can be parsed. This also worked, but required a lot of code to parse the resulting images and identify things like labels, and coordinate locations. I got tired of having to figure how to extract information from an SVG. (3) Use a wrapper on specific graphics functions that records the function arguments. This turns out to be a bit too high level, as I have to manually massage inputs. E.g. handle both xy plots and formula + data plots. (We teach both styles.) Are there any other ideas that I can try? My students are using an RMarkdown worksheet and answering questions by putting code in specific chunks. I've already hooked into knitr so I can record the chunk lines as they are being run and get the results and side-effects. Thanks, Reed -- Reed A. Cartwright, PhD Associate Professor of Genomics, Evolution, and Bioinformatics School of Life Sciences and The Biodesign Institute Arizona State University ================== Address: The Biodesign Institute, PO Box 876401, Tempe, AZ 85287-6401 USA Packages: The Biodesign Institute, 1001 S. McAllister Ave, Tempe, AZ 85287-6401 USA Office: Biodesign B-220C, 1-480-965-9949 Website: http://cartwrig.ht/ ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.